1. Field of the Invention
This invention generally relates to writing implements, and more specifically to pens having a self-contained source of illumination.
2. Description of the Prior Art
It is not uncommon to provide a writing implement, such as a pen, with a source of illumination so that the user of the lighted pen can effectively write on a surface in a dark environment. One early solution to the problem of writing in the dark included a conventional pen having a slim flashlight attached to the pen's body. In use, the writer held both the pen and the attached flashlight, with the flashlight illuminating the pen tip and the surrounding area of the writing surface.
This crude aggregate was quickly improved by essentially integrating the flashlight elements into the body of the pen so that the pen would contain the source of illumination, and since the bulky flashlight was eliminated, the improved lighted pen was easier to grasp and use.
The lighted pens of the prior art typically include a lamp (an LED or an incandescent type lamp), a battery, and a contact switch which controls the flow of current between the battery and the lamp. The lamp may be located anywhere within the pen body or pen top portion, as long as its light output is directed to the pen tip.
Since all of these prior art lighted pens require a battery and a switch, there is limited space available for the actual writing components of the pen, including the ink cartridge, the advancing mechanism which selectively advances the ink cartridge so that the tip projects from the lower end of the pen, and the return spring which retracts the cartridge. Typically, to maintain a slender lighted pen, the battery, switch and lamp components are positioned within the pen top portion and a shortened ink cartridge and an advancing mechanism are located in the pen body. Unfortunately, in these prior art lighted pens, as the light from the lamp passes through the transparent pen body, some of the light is blocked by the ink cartridge, and the advancing mechanism, resulting in less light reaching the pen tip and the writing surface. Also, as some of the light is blocked by the pen components (e.g., the ink cartridge), shadows are created on the writing surface which tend to be distracting to the user.
To help direct light to the very tip of the pen, a waveguide may be provided within the body of the pen, between the lamp and the pen tip. U.S. Pat. No. 4,518,274 of Hanggi discloses a lighted pen which includes a battery, switch, and a lamp, all located in a top portion of the pen. The pen body includes a waveguide which directs the light from the lamp through the pen-body to the pen-tip where the light may illuminate the writing surface. Unfortunately, much of the light from the lamp is directed to the writing components and therefore less light reaches the writing surface.
U.S. Pat. No. 4,890,204 of Lin et al. discloses a pen having a battery, switch and lamp all located within a top portion of the pen. Light from the lamp enters a hollow body portion of the pen and is directed to the pen tip by a reflective surface located along the inside walls of the pen body. Much of the light entering the pen body will be blocked (or otherwise reflected away from the pen tip) by the ink cartridge which is also located within the pen body.
One attempt to overcome the problem of directing light from the lamp to the pen-tip includes positioning the lamp as close as possible to the tip of the pen. U.S. Pat. No. 5,131,775 of Chen discloses an illuminating pen having a battery and switch located in a top portion of the pen, and an LED-type lamp located immediately adjacent to the tip of the pen. An advancing mechanism which is also positioned in the top of the pen, is used to selectively advance an ink cartridge sufficiently along the length of the pen to project the ink tip from the lower portion of the pen so that the pen may be used to write.
Although the lighted pen arrangement disclosed in U.S. Pat. No. 5,131,775 will provide light to the immediate vicinity of the pen tip, the pen is relatively complex because the lamp is positioned remote from its power supply and controlling switch. Also, since the LED lamp disclosed in U.S. Pat. No. 5,131,775 is located at the very tip of the pen, the LED lamp must be shaped similar to a truncated cone and must include a central bore to accommodate passage of the retractable ink cartridge. The LED lamp of this prior art lighted pen is not a readily available item and must be custom manufactured. Customizing parts for any device, such as this prior art pen will only increase the cost of the final product.
Although lighted pens having a light source that is located immediately adjacent to the pen tip, such as the pen disclosed in U.S. Pat. No. 5,131,775, effectively illuminate the pen tip and adjacent writing surface, the barrel of the pen (or the pen housing) remains dark during its operation, losing an opportunity to back-light a pattern, design, logo, advertisement, or indicia and display or otherwise creating an entertaining or decorative effect.
It would be beneficial to provide a lighted pen which includes a lamp, battery, and switch in a top portion of the pen and an ink cartridge and advancing mechanism located in a pen body, wherein the light from the lamp is directed through the pen, body around the ink cartridge and advancing mechanism to the tip. The light from the lamp should illuminate both the pen tip and simultaneously back-light a display portion of the pen body so that a pattern, design, logo, advertisement, or indicia located on the pen body may be illuminated when the pen is in use.
Accordingly, it is an object of the present invention to provide a lighted pen having a self-contained light source, which overcomes the deficiencies of the prior art.
It is another object of the present invention to provide such a lighted pen which includes a light source, a battery and a switch, wherein a display portion of the pen's housing and the pen tip are efficiently illuminated by a single light source.
It is another object of the present invention to provide such a lighted pen wherein the light from the lamp is directed to the pen tip and the display portion of the pen housing and not blocked by mechanical elements of the pen.
It is another object of the present invention to provide such a lighted pen which is inexpensive to manufacture and easy to operate.
It is another object of the present invention to provide a lighted pen having a translucent body, a top portion, and a self-contained light source wherein light generated from the light source is directed to both the pen tip and the walls of the translucent body.